Wall thinning of rubber hoses or the other rubber products has been studied for the purpose of reduction in weight and cost, and as one technique therefor, high rigidity rubber materials have been utilized. In order to increase rigidity of rubber materials, it is common to increase the amount of a carbon black as a reinforcing agent or to add a thermoplastic resin. However, these exhibit high rigidity in an ordinary temperature region, but are ineffective in a high temperature region.
Patent Document 1 discloses a rubber material of a sulfur vulcanization system, in which 150 to 250 parts by weight of a carbon black is blended with 100 parts by weight of Ethylene-Propylene-Diene Methylene linkage (EPDM), as a rubber material for oil-resistant hoses. In this blending system, however, stress characteristics applicable to thin-walled products cannot be obtained.
Patent Document 1: JP-A-2004-204924